Closing The Deal

Photography by Gary Blount

Sport Truck, December 01, 2005

In the Oct. '05 issue of Sport Truck, we started the task of powering up a GM Vortec big-block powerplant in a '96 Chevy Crew Cab dualie. The goal was to increase the amount of torque the fuel-injected big-block produced without negatively affecting fuel economy because this truck is a daily driver and frequent tow pig. We began by having Superior Automotive port the factory iron cylinder heads and upgrading the valves. The flow numbers the shop achieved with the undersized heads were very impressive. When the time came to reinstall the cylinder heads, we changed the plan at the shop and veered away from the combination the shop routinely installs in this motor for maximum power. Fuel prices had reached record levels in California, and with no end to the lunacy at the gas pumps in sight, we wimped out and had the shop keep the compression ratio low and the camshaft small. We still knew we'd gain torque, just not the amount we would have by bumping up the compression ratio and feeding the beast $3 a gallon for premium fuel every day.

When we went to install the heads and new valvetrain, we ran across a couple of problems that kept us from running the editorial last month, but we'll cover them in detail this round. As we stated in the last installment, we opened up the heads to flow better numbers, and we saw exceptional improvements, especially after replacing the intake and exhaust valves with larger Manley stainless swirls. The intake valve changed from 2.060 to 2.190 inches, and the exhaust changed from 1.720 to 1.800 inches, as well. This month, we are going to reinstall the cylinder heads and swap the stock GM valvetrain in favor of Comp Cams' off-the-shelf Gen V hydraulic roller cam, which is a plug-and-play setup. With this cam, you don't need to worry about degreeing the cam, because Comp Cams sets the centerline for you. This cam has 0.510 inch of lift, which we are going to increase with 1:8.1 rocker arms that will bring the lift closer to 0.550 inch. The conversion from a standard hydraulic flat tappet cam to a Comp Cams' full roller will also net a few more ponies by reducing friction in the valvetrain.

The first problem that came up during the installation was that 1996 was a cross-over year for the big-block in GM 1-ton trucks. This means that you could have one of a variety of different cylinder blocks between the framerails, depending upon when your truck was built. It would appear that both Gen V and Gen VI blocks were used, and we found out the hard way that there are a couple of differences between them. First off, the snout of the cam on the Gen V is stepped down and uses a completely different method of cam retention than the older-style block. This dramatically limits your off-the-shelf cam selection. Plus, there are no adjustable timing chains available for the newer-style cam, which means you are forced to either convert to the standard cam and timing cover, and work out the ignition pulse that is read by a sensor mounted in the timing chain cover, or pick from the narrower selection of Gen VI camshafts.

The second problem we encountered occurred when reinstalling the stock, low-profile valve covers, which hit the poly locks. If you decide to convert the Gen V to a roller system, make sure you ask for shorty poly locks for the rockers, because the long locks hit the valve cover. Forget about getting a taller cover, because the throttle body sits right atop the passenger-side valve cover. Should you decided to do these mods, it's essential you order the correct cam for your engine. Here is a list of descriptions that will help you identify your engine block.

Superior made sure the static compression ratio of our 454 stayed at 8.5:1, which ensured that we could pump 89 octane fuel into the tank under normal commuting conditions and switch to premium fuel, when the strains of towing a load demanded it. We were impressed with the power figures and the adjustability of this upgrade after all was said and done. We ran the combo on the dynamometer and found as much as 58 hp and 63 lb-ft of torque increase over the stock configuration, but that's not the impressive part. We liked that the powerband was spread out over 2,000 rpm. The truck retained its dismal 10-1/2-mpg fuel consumption but, with the additional torque on tap, was much easier to drive and tow with.

Dyno testing was conducted with an Innovative Motorsports band air/fuel ratio monitor plumbed into the exhaust system. Using this handy tuning tool, we noticed that the mid-throttle and open-throttle air/fuel ratios were in the 10s. This is way too rich, which would leave us to speculate that there is an additional 10 more ponies to be had with an air/fuel ratio closer to 13 or 14:1 on the top end. We also noticed a sizeable flat spot just off idle in the throttle response under light acceleration that we'll attend to in our next round of tuning.

Check in next month, when we use Innovative Motorsports tuning tools to dial in the tune.

PRICES (Found at Summit Racing)

DESCRIPTION

COST

Computer Tune

$350

Cam #: 01-445-8

$245

Lifters #: 854-16

$425

Pushrods (length to fit)

$88

Rockers #: 1128:16

$311.29

Head Work by Superior

$1,499

Total

$2,918.24

CASTING #

TYPE

YEAR

ENGINE

10069282

366T

'90-'91

4-bolt, Mark IV, Tall deck

10069284

427T

Various

4-bolt, Mark IV, Tall deck

10069286

454

'90-'91

4-bolt, Mark IV, Short deck

10114182

454

'91-and-later

4-bolt, Gen V

10114183

366T

'91-and-later

4-bolt, Gen V

10114184

427T

'91-and-later

4-bolt, Gen V

10134366

454T

Various

4-bolt, Bow Tie, Gen V, Tall deck

10185050

454

Various

4-bolt, Bow Tie, Gen V, Short deck

10237297

454

'96-and-later

4-bolt, Vortec 7400, "L-29" Gen VI

10237300

502

'96-and-later

4-bolt, Gen VI, 4.466-inch bore

12550312

427T

'96-and-later

4-bolt, Gen VI, 4.250-inch bore, fuel pump and clutch linkage boss

12550313

454

'91-and-later

4-bolt, Gen V crate motor, Gen VI, 4.250-inch bore, fuel pump boss

12556110

496

'01-and-later

4-bolt, Gen VII 8.1L, Vortec 8100, Truck

12561357

454

'96-and-later

4-bolt, Gen VI

12561358

502

Various

4-bolt, Gen VI

14015443

454

'87-'90

2- or 4-bolt, Mark IV, Truck, Motorhome

14015445

454

'78-'90

2- or 4-bolt

14044807

454T

Various

4-bolt, Bow Tie, Mark IV, Tall deck, 4.25- or 4.495-inch bores

14096859

502

Various

4-bolt, Gen V, HO

24502504

454

Race

4-bolt, Bow Tie, Gen V, 9.8 "Short" deck

24502506

454T

Race

4-bolt, Bow Tie, Gen V, 10.2 Tall deck height

1.We converted our hydraulic tappet cam to a roller. This doesn't help noise but reduces wear and will add a couple horsepower. Of course, you would have to order a custom cam from Comp Cams, but you would save yourself about $400, if you lift it with a hydraulic flat tappet cam. If your big-block is already a roller motor (some are), you won't need the pushrods or roller lifters, which will save you some money.

1.We converted our hydraulic tappet cam to a roller. This doesn't help noise but reduces w

2.The roller lifters are longer than the stock units. A new pushrod length will need to be used to accommodate the new lifters. Stock lifters are set off center of the cam to make the lifter rotate in the lifter bore. This helps reduce lifter wear. The roller on the roller lifters ride on the cam but generate less friction heat.

2.The roller lifters are longer than the stock units. A new pushrod length will need to be

3.Due to the longer lifters, you will need two new lengths of pushrods. The exhaust (longer) pushrod will be 8.550 inches, and the intake will need to be 7.550 inches in length. With new lifters, you will also want to have a fresh pushrod surface, anyway.

3.Due to the longer lifters, you will need two new lengths of pushrods. The exhaust (longe

4.The new rockers were made adjustable with poly locks. The poly locks needed a threaded shaft to fasten the rocker to. ARP rocker studs were installed by Superior Automotive for rocker deflection elimination, and they'll provide a threaded body for the poly locks.

4.The new rockers were made adjustable with poly locks. The poly locks needed a threaded s

5.As we discussed last month, a 1.8:1 roller rocker was used to increase the cam lift to 0.550 inch.

5.As we discussed last month, a 1.8:1 roller rocker was used to increase the cam lift to 0

6.The old-school big-block design, with meaty 4-bolt main caps and thick rods, is an awesome platform for building power.

6.The old-school big-block design, with meaty 4-bolt main caps and thick rods, is an aweso

7.Superior's labor involves a complete port and polish, larger valves, a three-angle valve job, and a surface for the desired compression ratio.

8.Also included in Superior's head work is some new hardware: larger valves, anti-rotator cups, springs, keepers, locks, and ARP rocker studs, all of which come installed as a complete ready-to-install head, at a damn good price of $1,400.

8.Also included in Superior's head work is some new hardware: larger valves, anti-rotator

9.Here is a good indicator of which block you might have. The pushrod girdles are stamped with the engine model.

9.Here is a good indicator of which block you might have. The pushrod girdles are stamped

10.Here's our off-the-shelf cam's specs. It has a 0.510 lift, but that's based on a stock 1.7:1 rocker ratio. If you dived 1.7 into 0.510, you will get 0.300, which is the actual lift on the cam lobe. We used a 1:8.1 rocker, so we multiply the 1.8 by 0.300 and end up with a gross lift of 0.540.

10.Here's our off-the-shelf cam's specs. It has a 0.510 lift, but that's based on a stock

11.The new big-blocks from GM use a cam retainer. This is how they keep the cam from drifting in and out.

11.The new big-blocks from GM use a cam retainer. This is how they keep the cam from drift

12.These new cams also have a different cam snout to accommodate the cam locator. This is where the confusion may come in. Some of the '96-'97 GM big-blocks may have an engine with either the standard or Gen V cam. Make sure you figure it out what you have before you starting trying to ordering parts.

12.These new cams also have a different cam snout to accommodate the cam locator. This is

13.The stock Gen V timing chain is thinner than an earlier style cam, and the three bolts that hold the cam on are a smaller diameter.

13.The stock Gen V timing chain is thinner than an earlier style cam, and the three bolts

14.The stock timing chain cover is cast alloy and ribbed for structure, because it does more than simply hold in some oil and seal the crank snout. The Gen V uses a crank trigger that mounts in the timing chain cover to provide the injection system with an rpm signal.

14.The stock timing chain cover is cast alloy and ribbed for structure, because it does mo

15.On assembly, make sure there is a 0.250-inch gap between the block and lifter link bar in the cam rotation. We had no problems, but it was close, and you know how manufacturers change things up, so just make sure you check the clearance.

15.On assembly, make sure there is a 0.250-inch gap between the block and lifter link bar

16.This really bitchin' cam degree tool by Comp Cams came in handy for telling us where the cam was in relation to the crank. The stock timing chain gear doesn't provide cam adjustment, and as far as we know, there is no adjustable timing chain for this style cam. The cam was cut on a 112-degree centerline and in the stock timing chain alignment installed at 108 degrees. If you subtract what the cam was cut on from how it actually installed, you will have the total center. So, 108 from 112 is actually 110 degrees.

16.This really bitchin' cam degree tool by Comp Cams came in handy for telling us where th

17.The cam is not radical, but it's merely slightly enhanced. So, the adjustment on the poly locks is the same as a hydraulic tappet setup. Remove the lash and three quarters of a turn more sets the adjustment.

17.The cam is not radical, but it's merely slightly enhanced. So, the adjustment on the po

18.Here is the reluctor wheel that provides a rotation signal through a sensor. This has to fit under the timing chain cover, which is another reason why the timing chain is thin.

18.Here is the reluctor wheel that provides a rotation signal through a sensor. This has t

19.With the cover in place, you can see how the sensor interacts with the reluctor. So, if you wanted to convert your Gen V to an early cam, you would need to figure out a way to use something like an MSD crank trigger to provide the proper pulse and frequency to the ECM.

19.With the cover in place, you can see how the sensor interacts with the reluctor. So, if

20.There have been great advancements to the combustion engine in the past few years. One of these advancements is sealing management. Later gasket designs provide a more complete seal and a longer sealing life. This adds to the life and performance of the engine.

20.There have been great advancements to the combustion engine in the past few years. One

21.The intake is comprised of a two-piece casting. The bottom section holds the injectors and some sensors. Even though we disassembled the intake completely, you won't need to remove the fuel rails or injectors. This will make your disassembly and reassembly easier.

21.The intake is comprised of a two-piece casting. The bottom section holds the injectors

22.When you order the 1.8:1 rockers from Comp Cams or Summit Racing, make sure you instruct them to replace the standard poly locks with the shorty poly locks. Otherwise, the standard locks will interfere with the valve cover. Replacing the valve cover with a taller version is not an option because the throttle body sits right over the passenger-side valve cover.

22.When you order the 1.8:1 rockers from Comp Cams or Summit Racing, make sure you instruc

23.You can see the shorty poly locks sit significantly lower (left) than the standard locks (right).

23.You can see the shorty poly locks sit significantly lower (left) than the standard lock

24.The exhaust manifold uses studs for fasteners for half of the exhaust system. When we pulled the exhaust manifolds off, the nuts stuck to the studs and pulled them out of the head. To ensure a good seal, make sure the studs are installed first and use some Loctite to hold the studs in place. Then, install the manifolds and nuts, and torque them down.

24.The exhaust manifold uses studs for fasteners for half of the exhaust system. When we p

25.Another way to ensure the exhaust has a good seal is to use high-temp ATV around the gasket.

25.Another way to ensure the exhaust has a good seal is to use high-temp ATV around the ga

26.The rest of the reinstallation process involves simply plugging in the electronics and accessories.

26.The rest of the reinstallation process involves simply plugging in the electronics and

This mod will work without an after-cat exhaust, but since our truck's old exhaust was shot and we wanted to ensure the exhaust was free-flowing, we installed a Bassani after-cat system to fix our rotted exhaust problems.

This mod will work without an after-cat exhaust, but since our truck's old exhaust was sho

The after-cat was easy to install. We simply cut the stock exhaust off at the right length and slid the Bassani system on and clamped it in place.

The after-cat was easy to install. We simply cut the stock exhaust off at the right length

The ECM needed a new program, so it also needed to be sent to Z-Industries to have a specially tailored program put in so the mods would render a similar result.

The ECM needed a new program, so it also needed to be sent to Z-Industries to have a speci

We had Ron at Z-Industries work with us on a premium program that would work with this combination of parts and cylinder head mods. Stay tuned, because the next installment of this series will optimize the tune and render the best results.

We had Ron at Z-Industries work with us on a premium program that would work with this com

Another mod that can be made is to upgrade the factory 60mm throttle body to BBK's 80mm throttle body. This will make sure you have the best possible throttle response by adding more available air to the intake tract with less throttle position.

Another mod that can be made is to upgrade the factory 60mm throttle body to BBK's 80mm th